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Correct Answer: both a and b
excessive amounts of nitrate in water can lead to several environmental and ecological issues, primarily due to a process known as eutrophication. here’s an expanded explanation:
when nitrate from agricultural fertilizers or other sources leaches into water bodies such as rivers, lakes, and streams, it acts as a nutrient boost for aquatic plants, especially algae. algae use these nutrients to grow more rapidly than they would under normal nutrient conditions. this phenomenon is often referred to as an algal bloom.
algal blooms have a direct effect on the clarity and quality of water. as algae proliferate, they form dense mats that float on the surface of the water or cloud the water column. this dense layer of algae blocks sunlight from reaching other aquatic plants beneath the surface. these submerged plants, deprived of light, are unable to perform photosynthesis effectively and begin to die off.
the effects of algal blooms are not limited to blocking sunlight. when the algae eventually die, their decomposition becomes a food source for bacteria and other microorganisms. this decomposition process consumes a significant amount of the dissolved oxygen in the water, which is critical for the survival of fish and other aquatic organisms. this reduction in dissolved oxygen levels can lead to hypoxic conditions, commonly known as dead zones, where oxygen levels are too low to support most marine life.
furthermore, as these microorganisms decompose the algae, they also release byproducts such as ammonia and further deplete the oxygen, exacerbating the hypoxia. this lack of oxygen can cause massive die-offs of local fish populations and can disrupt the entire aquatic ecosystem.
in summary, excessive nitrate levels in water bodies lead to enhanced algae growth, which subsequently causes a reduction in sunlight penetration and a severe decrease in dissolved oxygen levels due to the decomposition of algae. this series of events harms aquatic life and can lead to ecological degradation of water bodies, affecting biodiversity and water quality. thus, the correct answer to the effects of excessive nitrates in water includes both the rapid growth of algae and the reduction of dissolved oxygen, making "both a and b" the correct choice.
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